Case Study: Necrotizing Fasciitis in a Patient With Obesity and Poorly Controlled Type 2 Diabetes

E.N. is a 60-year-old white woman who presented at the hospital with high fever, chills, and severe pain at the base of her neck. She was unable to flex or rotate her neck because of pain and swelling. She recalled that 3 days before admission, there was an unusually warm winter day, and she walked in a nearby park enjoying the weather. She recalled an itching and painful sensation that she initially attributed to a spider/insect bite on her upper back, which gradually progressed to severe pain and swelling over the next 2 days.

Her medical history was significant for type 2 diabetes for the past 5 years, class 2 obesity (body mass index 37.5 kg/m²), and hypertension for the past 10 years. Her medications were glyburide (Micronase), 5 mg twice daily, and verapamil (Calan SR), 240 mg daily. She did not smoke or drink alcohol. Her family history was significant for mother with type 2 diabetes and hypertension.

At admission, E.N. was febrile (temperature 40°C), tachypneic (respiratory rate 20), tachycardic (heart rate 120), and hypertensive (blood pressure 164/69 mmHg). Physical examination revealed a large area of wood-like induration (5 × 6 inches) extending from the back of the neck forward to the chin and downward to the upper back. The skin was darkly erythematous, and there was a central area of excoriation with yellow crust. Admission laboratory studies revealed hemoglobin 13.7 g/dl, white blood count 13.6 K/mm³, bands 10%, plasma glucose 356 mg/dl, and hemoglobin A_1c 10.2%. Blood cultures were performed, and the patient was treated with high-dose intravenous antibiotics.

1. What is the diagnosis?

2. How should this patient be managed?

3. What are the microorganisms producing this fulminating infection?

4. How is the patient predisposed to developing this condition?

E.N. underwent computed tomography (CT) imaging of the neck and chest, which showed extensive gas formation in the soft tissues of the right back neck dissecting along the fascial planes toward the front neck and upper back. Based on clinical presentation and CT images (Figures 1 and 2), E.N. was diagnosed with necrotizing fasciitis.

CT diagnostic criteria for necrotizing fasciitis are asymmetric fascial thickening associated with fat stranding and gas tracking along the fascial planes. In advanced cases, the infection can extend to the adjacent muscles, with gas present within the muscle mass characteristic of myonecrosis. Imaging modalities detecting the presence of gas in the soft tissues are plain radiography of the involved areas, ultrasonography of the scrotum in the case of Fournier’s gangrene, CT imaging, and magnetic resonance imaging. CT imaging has the advantage of being readily available and offering an excellent depiction of the extent of soft tissue necrosis and of possible coexisting deep abdominal or pelvic abscesses.

With the diagnosis established, E.N. was immediately taken to the operating room for incision and debridement. Necrotizing fasciitis is a surgical emergency because the infection can spread in the subcutaneous tissue over a period of hours. Frequently, the severity and the extent of the infection are not initially appreciated. Delay in accurate diagnosis is associated with poor prognosis.

In E.N.’s case, surgery revealed extensive soft tissue necrosis of the cervical fascia extending to the carotid sheath, with involvement of the right trapezius and right sternocleidomastoid muscle. There was a large quantity of necrotic, foul-smelling tissue and thin, watery, brown discharge (classically described as “dishwater pus”). Gram stain of necrotic tissue specimens showed a polymicrobial bacterial population (many Gram-positive and Gram-negative cocci and many Gram-negative bacilli), and the culture identified staphylococcus epidermidis, streptococcus viridans, bacteroides ureolyticus, pseudomonas aeruginosa, proteus mirabilis, and enterococcus faecalis.

E.N. underwent multiple surgical debridements and was treated with large doses of intravenous antibiotics: clindamycin (Cleocin), 900 mg every 8 hours, and gentamicin (Garamycin), 450 mg every 24 hours. Blood cultures were repeatedly negative. Despite aggressive surgical and medical management, the patient developed septic shock and cardiac arrest, unresponsive to resuscitation attempts.

This case illustrates the evolution of necrotizing fasciitis, which is a deep and devastating soft tissue infection. In 80% of cases, the infection develops as an extension from a skin lesion (i.e., minor abrasion, insect bite, or injection site), but in 20% of cases, there is no visible skin lesion. The etiology can be monomicrobial (i.e., group A β-hemolytic streptococcus pyogenes, staphylococcus aureus, or peptostreptococcus) or polymicrobial (mixed aerobe and anaerobe bacteria). Risk factors for developing necrotizing fasciitis are uncontrolled diabetes, alcoholism, morbid obesity, advanced atherosclerotic disease, and decubitus ulcers.

Diabetes is the underlying illness in half of all cases of necrotizing fasciitis. Diabetic patients may be predisposed to necrotizing fasciitis by the tissue hypoxia caused by arteriosclerosis and the immunodeficiency associated with poor glycemic control. Neutrophil chemotaxis, adherence, phagocytosis, and intracellular oxidative killing have been shown to be defective in diabetes.

The pathological hallmark of necrotizing fasciitis is thrombosis of subcutaneous arteries and arterioles leading to extensive soft tissue necrosis. Early and aggressive surgical debridement of all involved tissues, combined with combination intravenous antibiotic therapy with broad spectrum coverage, is the cornerstone of therapy.

Early diagnosis based on clinical presentation and imaging modalities is essential in initiating medical and surgical treatment. In the absence of rapid control of the spread of the infection, necrotizing fasciitis progresses to disseminated vascular coagulation, septic shock, and death (cumulative mortality rate 34%).

• Necrotizing fasciitis is a severe soft tissue infection occurring in patients with diabetes, morbid obesity, alcoholism, advanced atherosclerotic disease, and decubitus ulcers.

• Early diagnosis is essential for patients’ survival.

• CT imaging is very useful in identifying the presence of gas in soft tissues and gas tracking along the fascial planes.

• Aggressive surgical debridement and combination, broad-spectrum coverage intravenous antibiotic therapy are the cornerstones of therapy.